Re: [dpdk-dev] Max throughput Using QOS Scheduler

[Srikanth Akula <srikanth044@gmail.com>]

Hi Cristian,


Thank you very much for your points and it should really help me in fixing
few issues we might have.

thanks again !

Regards,
srikanth


On Thu, Nov 6, 2014 at 12:37 PM, Dumitrescu, Cristian <
cristian.dumitrescu@intel.com> wrote:

>  Hi Srikanth,
>
>
>
> >>Is there any difference between scheduler behavior  for above two
> scenarios  while enqueing and de-queueing ??
>
> All the pipe queues share the bandwidth allocated to their pipe. The
> distribution of available pipe bandwidth between the pipe queues is
> governed by features like traffic class strict priority, bandwidth sharing
> between pipe traffic classes, weights of the queues within the same traffic
> class, etc. In the case you mention, you are just using one queue for each
> traffic class.
>
>
>
> Let’s take an example:
>
> -        Configuration: pipe rate = 10 Mbps, pipe traffic class 0 .. 3
> rates = [20% of pipe rate = 2 Mbps, 30% of pipe rate = 3 Mbps, 40% of pipe
> rate = 4 Mbps, 100% of pipe rate = 10 Mbps]. Convention is that traffic
> class 0 is the highest priority.
>
> -        Injected traffic per traffic class for this pipe: [3, 0, 0, 0]
> Mbps => Output traffic per traffic class for this pipe: [2 , 0, 0, 0] Mbps
>
> -        Injected traffic per traffic class for this pipe: [0, 0, 0, 15]
> Mbps => Output traffic per traffic class for this pipe: [0, 0, 0, 10] Mbps
>
> -        Injected traffic per traffic class for this pipe: [1, 10, 2, 15]
> Mbps => Output traffic per traffic class for this pipe: [1, 3, 2, 4] Mbps
>
>
>
> Makes sense?
>
>
>
> >>Queue size is 64 , and number of packets enqueued and dequeued is 64 as
> well.
>
> I strongly recommend you never use a dequeue burst size that is equal to
> enqueue burst size, as performance will be bad.
>
>
>
> In the qos_sched sample app, we use [enqueue burst size, dequeue burst
> size] set to [64, 32], other reasonable values could be [64, 48], [32, 16],
> etc. An enqueue burst bigger than dequeue burst will cause the big packet
> reservoir which is the traffic manager/port scheduler to fill up to a
> reasonable level that will allow dequeu to function optimally, and then the
> system regulates itself.
>
>
>
> The reason is: since we interlace enqueue and dequeue calls, if you push
> on every iteration e.g. 64 packets in and then look to get 64 packets out,
> you’ll only have 64 packets into the queues, then you’ll work hard to find
> them, and you get out exactly those 64 packets that you pushed in.
>
>
>
> >>And what is the improvements i would gain if i move to DPDK 1.7 w.r.t
> QOS ?
>
> The QoS code is pretty stable since release 1.4, not many improvements
> added (maybe it’s the right time to revisit this feature and push it to the
> next level …), but there are improvements in other DPDK libraries that are
> dependencies for QoS (e.g. packet Rx/Tx).
>
>
>
> Hope this helps.
>
>
>
> Regards,
>
> Cristian
>
>
>
>
>
>
>
> *From:* Srikanth Akula [mailto:srikanth044@gmail.com]
> *Sent:* Thursday, October 30, 2014 4:10 PM
> *To:* dev@dpdk.org; Dumitrescu, Cristian
> *Subject:* Max throughput Using QOS Scheduler
>
>
>
> Hello All ,
>
>
>
> I am currently trying to implement QOS scheduler using DPDK 1.6 . I have
> configured 1 subport , 4096 pipes for the sub port and 4 TC's and 4 Queues .
>
>
>
> Currently i am trying to send packets destined to single Queue of the
> available 16 queues of one of the pipe .
>
>
>
> Could some body explain what could be the throughput we can achieve using
> this scheme.  The reason for asking this is , i could sense different
> behavior each time when i send traffic destined to different destination
> Queues  .
>
>
>
> for example :
>
>
>
> 1. << Only one stream>>> Stream destined Q0 of TC0 ..
>
>
>
>
>
> 2. << 4 streams >>>> 1st Stream destined for Q3 of Tc3 ...
>
>                                  2nd stream destined for Q2 of Tc2
>
>                                  3rd stream destined for Q1 of TC1
>
>                                  4th Stream destined for Q0 of TC0
>
>
>
> Is there any difference between scheduler behavior  for above two
> scenarios  while enqueing and de-queueing ??
>
>
>
> Queue size is 64 , and number of packets enqueud and dequeued is 64 as
> well.
>
> And what is the improvements i would gain if i move to DPDK 1.7 w.r.t QOS ?
>
>
>
>
>
> Could you please clarify my queries ?
>
>
>
>
>
> Thanks & Regards,
> Srikanth
>
>
>
>
>
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